// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CC_ANIMATION_SCROLL_OFFSET_ANIMATION_CURVE_H_
#define CC_ANIMATION_SCROLL_OFFSET_ANIMATION_CURVE_H_

#include <memory>

#include "base/macros.h"
#include "base/time/time.h"
#include "cc/animation/animation_curve.h"
#include "cc/animation/animation_export.h"
#include "ui/gfx/geometry/scroll_offset.h"

namespace cc {

class TimingFunction;

class CC_ANIMATION_EXPORT ScrollOffsetAnimationCurve : public AnimationCurve {
public:
    enum class DurationBehavior { DELTA_BASED,
        CONSTANT,
        INVERSE_DELTA };
    static std::unique_ptr<ScrollOffsetAnimationCurve> Create(
        const gfx::ScrollOffset& target_value,
        std::unique_ptr<TimingFunction> timing_function,
        DurationBehavior = DurationBehavior::DELTA_BASED);

    static base::TimeDelta SegmentDuration(const gfx::Vector2dF& delta,
        DurationBehavior behavior,
        base::TimeDelta delayed_by);

    ~ScrollOffsetAnimationCurve() override;

    void SetInitialValue(const gfx::ScrollOffset& initial_value,
        base::TimeDelta delayed_by = base::TimeDelta());
    bool HasSetInitialValue() const;
    gfx::ScrollOffset GetValue(base::TimeDelta t) const;
    gfx::ScrollOffset target_value() const { return target_value_; }
    void UpdateTarget(double t, const gfx::ScrollOffset& new_target);
    void ApplyAdjustment(const gfx::Vector2dF& adjustment);

    // AnimationCurve implementation
    base::TimeDelta Duration() const override;
    CurveType Type() const override;
    std::unique_ptr<AnimationCurve> Clone() const override;
    std::unique_ptr<ScrollOffsetAnimationCurve>
    CloneToScrollOffsetAnimationCurve() const;

private:
    ScrollOffsetAnimationCurve(const gfx::ScrollOffset& target_value,
        std::unique_ptr<TimingFunction> timing_function,
        DurationBehavior);

    gfx::ScrollOffset initial_value_;
    gfx::ScrollOffset target_value_;
    base::TimeDelta total_animation_duration_;

    // Time from animation start to most recent UpdateTarget.
    base::TimeDelta last_retarget_;

    std::unique_ptr<TimingFunction> timing_function_;
    DurationBehavior duration_behavior_;

    bool has_set_initial_value_;

    DISALLOW_COPY_AND_ASSIGN(ScrollOffsetAnimationCurve);
};

} // namespace cc

#endif // CC_ANIMATION_SCROLL_OFFSET_ANIMATION_CURVE_H_
